4 ms·I'm guessing Fastmail since you've posted about them before and the format looks like their aliasesby KomoD 2y agoI'm guessing Fastmail since you've posted about them before and the format looks like their aliasesgreyface- 2y agoThe hostname in the Received: header (phl-compute-07.internal) is consistent with Fastmail.mvdtnz 2y agoCorrect. It's a Fastmail masked email address.